This invention relates generally to the transmission of data via broadcast digital television signals, for example digital television signals which follow the American Television Standards Committee (ATSC) format, and more particularly to the transmission of global positioning system (GPS) aiding information by such techniques.
Starting with the first ATSC standard digital television broadcast in the late 1990xe2x80x2s, digital television broadcasting is rapidly expanding in the United States. By the end of 2000, more than 166 digital television transmitters were in operation. The FCC has set a goal that by 2006 all television broadcasting will be on recently assigned digital channels with the analog channels being returned to the government for other applications.
Sophisticated data compression techniques and the availability of increased digital signal processing capabilities make it possible to transmit high quality audio and video information in the same bandwidth as analog channels. In the television broadcast community, the Advanced Television Systems Committee (ATSC) created both the digital television standard and the high-definition television standard to take advantage of these technological advances. These standards are often referred to as ATSC digital TV or simply ATSC. A current ATSC standard uses the amplitude modulated suppressed-carrier vestigial sideband modulation technique called VSB. The 8-VSB modulation is used in terrestrial xe2x80x9coff airxe2x80x9d broadcast systems and the 16-VSB modulation is proposed for higher data rate cable systems.
These standards are optimized for the broadcast of TV programming. However, the rapid expansion of digital TV broadcasting and the corresponding proliferation of digital television transmitters creates opportunities for the transmission of other types of data. Examples of other types of data include data to allow cell phones to compute their own location without the need for external processing, short messages, applications similar to those on pagers, stock quotes, web pages in text form, simple grid maps showing places of interest near a cell phone, TV programming guide, radio programming guide, bus schedules, advertisements for stores in the vicinity of the receiver, and all types of low data rate mobile-commerce information.
The television infrastructure is not always suited for these types of data. For example, the ATSC standard is geared towards a certain spectral efficiency, meaning that a certain amount of information is to be transmitted over a certain spectral bandwidth. Specifically, a bit rate which is high enough to support the broadcast of television programming must fit into the bandwidth allocated for a single television channel. With this operating requirement, a certain signal to noise ratio is required in order to successfully receive the broadcast signal. For example, the 19.2 Mbps ATSC standard broadcast data rate requires the receiver to have a theoretical signal-to-noise ratio of 15 dB.
However, other operating points may be more suitable for other types of data. For example, low data rate applications may benefit from a lower spectral efficiency but a more robust transmission. This type of signal may be recovered at much lower signal to noise ratios than required to receive digital television broadcasts, thus allowing reception in remote areas, indoors, or in locations where interference or multipath causes problems. In addition, simpler receivers may be used compared to those required to receive digital television broadcasts.
Thus, there is a need for systems and methods which can take advantage of the rapidly expanding digital TV (DTV) infrastructure, but for the transmission of data other than television programming. In particular, lower data rate transmissions which are more robust are of interest.
In general, in one aspect, the invention features a method, apparatus, and computer-readable media for providing satellite positioning system aiding information to a satellite positioning system receiver configured to determine the position of the satellite positioning system receiver using the satellite positioning system aiding information and the propagation time of a signal transmitted by a satellite in the satellite positioning system. It comprises providing the satellite positioning system aiding information; providing a digital television signal comprising a plurality of frames, each frame comprising a plurality of data segments; encoding the satellite positioning system aiding information as codewords; replacing data segments within the digital television signal with the codewords; and transmitting the digital television signal; wherein the satellite positioning system receiver receives the digital television signal and recovers the satellite positioning system aiding information.
Particular implementations can include one or more of the following features. The satellite positioning system is the global positioning system (GPS). The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system aiding information. The satellite positioning system aiding information comprises at least one of the group comprising a position of the satellite positioning system satellite; clock correction information for the satellite positioning system satellite; Doppler information for the signals transmitted by the satellite positioning system satellite; information regarding atmospheric effects on the signal transmitted by the satellite positioning system satellite; and identification of the satellite positioning system satellites that are visible to the satellite positioning system receiver. The digital television signal comprises at least one of the group comprising an American Television Standards Committee (ATSC) digital television signal; a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (DVB-T) signal; and a Japanese Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) signal.
In general, in one aspect, the invention features a method, apparatus, and computer-readable media for recovering satellite positioning system aiding information from a digital television signal. It comprises receiving the digital television signal, the digital television signal comprising a plurality of frames, each frame comprising a plurality of data segments, wherein at least one data segment has been replaced by at least one codeword representing the satellite positioning system aiding information; selecting the data segments which have been replaced by codewords; and recovering the satellite positioning system aiding information from the selected data segments.
Particular implementations can include one or more of the following features. The satellite positioning system is the global positioning system (GPS). The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system aiding information. The satellite positioning system aiding information comprises at least one of the group comprising a position of the satellite positioning system satellite; clock correction information for the satellite positioning system satellite; Doppler information for the signals transmitted by the satellite positioning system satellite; information regarding atmospheric effects on the signal transmitted by the satellite positioning system satellite; and identification of the satellite positioning system satellites that are visible to the satellite positioning system receiver. The digital television signal comprises at least one of the group comprising an American Television Standards Committee (ATSC) digital television signal; a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (DVB-T) signal; and a Japanese Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) signal.
In general, in one aspect, the invention features a method, apparatus, and computer-readable media for determining a position of a satellite positioning system receiver using a satellite positioning system. It comprises receiving at the satellite positioning system receiver a signal transmitted by a satellite in the satellite positioning system; receiving at the satellite positioning system receiver a digital television signal comprising a plurality of frames, each frame comprising a plurality of data segments, wherein at least one data segment has been replaced by at least one codeword representing satellite positioning system aiding information; selecting the data segments which have been replaced by codewords; recovering the satellite positioning system aiding information from the selected data segments; and determining a position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system aiding information.
Particular implementations can include one or more of the following features. The satellite positioning system is the global positioning system (GPS). The satellite positioning system aiding information comprises at least one of the group comprising a position of the satellite positioning system satellite; clock correction information for the satellite positioning system satellite; Doppler information for the signals transmitted by the satellite positioning system satellite; information regarding atmospheric effects on the signal transmitted by the satellite positioning system satellite; and identification of the satellite positioning system satellites that are visible to the satellite positioning system receiver. The digital television signal comprises at least one of the group comprising an American Television Standards Committee (ATSC) digital television signal; a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (DVB-T) signal; and a Japanese Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) signal. Implementations comprise determining a pseudo-range between the satellite positioning system receiver and a transmitter of the digital television signal based on a known component of the digital television signal; and determining a position of the satellite positioning system receiver based on the pseudo-range, the signal received from the satellite positioning system satellite and the satellite positioning system aiding information. In accordance with the present invention, digital data is transmitted as part of a digital television (DTV) broadcast signal by encoding the digital data as codewords and replacing some of the data segments in the DTV signal with the codewords. The use of long codewords results in a transmission which is more robust than the portions of the DTV broadcast signal used for television programming and can therefore be received at lower signal to noise ratios. The use of a finite set of codewords allows recovery of the digital data using a simple bank of correlators at the receiver.
In general, in one aspect, the invention features an apparatus for providing satellite positioning system aiding information to a satellite positioning system receiver configured to determine the position of the satellite positioning system receiver using the satellite positioning system aiding information and the propagation time of a signal transmitted by a satellite in the satellite positioning system. It comprises a second satellite positioning system receiver to receive the satellite positioning system aiding information; a channel coder to provide a digital television signal comprising a plurality of frames, each frame comprising a plurality of data segments; an encoder to encode the satellite positioning system aiding information as codewords; a packet multiplexer to replace data segments within the digital television signal with the codewords; and a transmitter to transmit the digital television signal; wherein the satellite positioning system receiver receives the digital television signal and recovers the satellite positioning system aiding information.
Particular implementations can include one or more of the following features. The satellite positioning system is the global positioning system (GPS). The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system aiding information. The satellite positioning system aiding information comprises at least one of the group comprising a position of the satellite positioning system satellite; clock correction information for the satellite positioning system satellite; Doppler information for the signals transmitted by the satellite positioning system satellite; information regarding atmospheric effects on the signal transmitted by the satellite positioning system satellite; and identification of the satellite positioning system satellites that are visible to the satellite positioning system receiver. The digital television signal comprises at least one of the group comprising an American Television Standards Committee (ATSC) digital television signal; a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (DVB-T) signal; and a Japanese Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) signal.
In general, in one aspect, the invention features an apparatus for recovering satellite positioning system aiding information from a digital television signal. It comprises a front end to receive the digital television signal, the digital television signal comprising a plurality of frames, each frame comprising a plurality of data segments, wherein at least one data segment has been replaced by at least one codeword representing the satellite positioning system aiding information; and a back end to select the data segments which have been replaced by codewords and to recover the satellite positioning system aiding information from the selected data segments.
Particular implementations can include one or more of the following features. The satellite positioning system is the global positioning system (GPS). The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system aiding information. The satellite positioning system aiding information comprises at least one of the group comprising a position of the satellite positioning system satellite; clock correction information for the satellite positioning system satellite; Doppler information for the signals transmitted by the satellite positioning system satellite; information regarding atmospheric effects on the signal transmitted by the satellite positioning system satellite; and identification of the satellite positioning system satellites that are visible to the satellite positioning system receiver. The digital television signal comprises at least one of the group comprising an American Television Standards Committee (ATSC) digital television signal; a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (DVB-T) signal; and a Japanese Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) signal.
In general, in one aspect, the invention features an apparatus for determining a position of a satellite positioning system receiver using a satellite positioning system. It comprises a front end to receive a signal transmitted by a satellite in the satellite positioning system, and to receive a digital television signal comprising a plurality of frames, each frame comprising a plurality of data segments, wherein at least one data segment has been replaced by at least one codeword representing satellite positioning system aiding information; a back end to select the data segments which have been replaced by codewords and to recover the satellite positioning system aiding information from the selected data segments; and a processor to determine a position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system aiding information.
Particular implementations can include one or more of the following features. The satellite positioning system is the global positioning system (GPS). The satellite positioning system receiver determines the position of the satellite positioning system receiver based on the signal received from the satellite positioning system satellite and the satellite positioning system aiding information. The satellite positioning system aiding information comprises at least one of the group comprising a position of the satellite positioning system satellite; clock correction information for the satellite positioning system satellite; Doppler information for the signals transmitted by the satellite positioning system satellite; information regarding atmospheric effects on the signal transmitted by the satellite positioning system satellite; and identification of the satellite positioning system satellites that are visible to the satellite positioning system receiver. The digital television signal comprises at least one of the group comprising an American Television Standards Committee (ATSC) digital television signal; a European Telecommunications Standards Institute (ETSI) Digital Video Broadcasting-Terrestrial (DVB-T) signal; and a Japanese Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) signal. The processor determines a pseudo-range between the satellite positioning system receiver and a transmitter of the digital television signal based on a known component of the digital television signal; and determines a position of the satellite positioning system receiver based on the pseudo-range, the signal received from the satellite positioning system satellite and the satellite positioning system aiding information.
The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.